This invention relates to a feed and takeoff assembly particularly adapted to transfer sheet stock from a first location, to a second location, to a third location, particularly in combination with the operation of a screen printing press.
The screen printing of the various types and thicknesses of paper and metal stock used in business, advertising and innumerable other applications has increased dramatically in the last few years. The demand for this type of printing often requires high-volume production which, in turn, demands efficiency in the printing process. The automatic and semi-automatic screen printing presses used in this type of work generally include a frame having a printing bed and a pivoting printing head mounted on the frame and holding a screen for placement over the printing bed above the stock to be printed which is placed thereon.
In order to achieve production efficiency and acceptable quality in large volume models of such presses, some kind of automatic or at least semi-automatic device to feed stock to or remove and deliver it from the press is critical. However, there is presently a lack of simple, inexpensive, reliable automatic equipment for feeding, registering and removing stock in connection with a printing press. Therefore, feeding and registering is often done by hand; the press is then activated; and, at best, an automatic takeoff, such as that shown in U.S. Pat. No. 3,860,231 to Claude H. Oltra and manufactured by American Screen Printing Equipment Company of Chicago, Ill., is used to automatically remove the stock.
There are also presently available complex systems of mechanical finger-type grippers which are built directly into the printing press to accomplish feeding, registration and delivery. These devices usually include three or more individual series of independently-operating grippers. One gripper set feeds, one gripper set registers, and two or more gripper sets act to remove the stock from the printing area and deliver it to a final position. Such gripper series are independent of one another and moved by a complex mechanical system of chains and linkages. They must be independently adjusted for various thicknesses and sizes of stock being printed. The expense of such equipment is prohibitive for small firms, and the cost of maintenance, because of possible breakdown and readjustment, is often high.